The influences of semiconductor optical amplifier parameters on all-optical wavelength conversion system with high speed polarization multiplexing-orthogonal frequency division multiplexing (PM-OFDM) are analyzed and simulated. The SOA parameters, such as gain saturation, optical confinement factor and carrier concentration in active region, are related to the wavelength conversion efficiency. Before achieving SOA gain saturation or nearby SOA gain saturation, the injection current, the carrier concentration, and the optical confinement factor effect on the SOA gain coefficient changing, and ultimately effect the wavelength conversion efficiency. The PM-OFDM signal with the rate of 40 Gbit/s is achieved directly without crosstalk after all-optical wavelength conversion when we improve the SOA parameters.